Dear Mrugen ji,
ESI is applicable when you have 10 and more employees (and not 8) irrespective of permanent, temporary, casual, part time, contractual or contract employee and irrespective of salary limit. This is except in Maharashtra, HP and in Assam.
In Maharashtra, HP and in Assam, ESI is applicable in factory when you have 10 and more coverable employees and in Shops and commercial establishment when you have 20 and more coverable employees.
Employees means employees including of employees of contractors also.